考虑界面效应的GFRP复合材料蠕变模型

建立了包含界面的玻璃纤维增强树脂复合材料(GFRP)蠕变混合率单胞模型，对GFRP的蠕变性能进行分析；并与GFRP在应力水平为初始弯曲强度的20%所对应的载荷下的弯曲蠕变实验结果进行对比。分析了界面模量、界面厚度、纤维连续性与形态以及位向等因素对复合材料蠕变性能的影响。结果表明:相较于不考虑界面效应的混合率模型，本模型具有更高的准确性，与实验结果更为吻合；界面模量反应了纤维与基体的结合程度，对复合材料的蠕变性能产生影响，其蠕变柔量随着界面模量的增大而减小；界面厚度的增大会导致复合材料的蠕变柔量略微增大；相较于连续纤维增强树脂复合材料，短切纤维毡增强树脂复合材料的蠕变性能更易受到界面效应的影响；纤维方向对复合材料蠕变性能有显著影响，随着纤维方向角的增大，复合材料蠕变柔量增大，但当纤维方向角达到60°后，纤维已基本失去载荷传递和增强能力，复合材料蠕变柔量不再继续随着纤维方向角的增大而增大。 

Creep model of GFRP composites considering interface effect

A unit cell model of creep mixing rate containing interface for glass fiber/resin composite (GFRP) was established to analyze the long-term creep property of GFRP. The experimental results of bending creep of GFRP under loads with the stress level of 20% of the initial bending strength were compared. The effects of interfacial modulus, interfacial thickness, fiber continuity, morphology and orientation on the long-term creep properties of composites were analyzed. The results show that this model is more accurate and more consistent with the experimental results compared with the mixing rate model without considering the interface effect. Interfacial modulus reflects the degree of binding between fiber and matrix, and affects the creep property of composite. The creep compliance decreases with the increase of interface modulus. The creep compliance of the composite increases slightly with the increase of the interfacial thickness. Compared with continuous fiber reinforced resin composites, the creep properties of chopped strand mat reinforced resin composite are more easily affected by interfacial effects. The fiber direction has a significant influence on the creep performance of composite materials. With the increase of fiber direction angle, the creep compliance of composite increases. However, when the fiber direction angle reaches 60°, the fiber has basically lost the load transfer and reinforcing ability, and the creep compliance of composite materials no longer increases with the increase of fiber direction angle.